The former England star backed Benitez's theory that most of football shares his manager's opinion.
"It looked like something that has been bothering Rafa for a while," Carragher told Sky Sports.
"It is something that people have always said in football, that the big teams get the decisions. Sometimes in the past Rafa felt that maybe they have had a few decisions especially at Old Trafford.
"Over the years the bigger teams get more decisions, so maybe there is a bit more pressure put on referees.
"As he said, they are all facts."